Dodge Cummins Diesel Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Have a 2006 3500 dually and want to run straight pipe. 4" or 5 best to run. Brand? want mandrel bend. Would like to hear from people that have run either.
Thanks..
 

·
Trying to learn
Joined
·
5,589 Posts
With mine, the muffler was cut out and a piece of pipe replaced it, still on the stock exhaust.
 
  • Like
Reactions: rghavana

·
Registered
Joined
·
4 Posts
Discussion Starter #4
Thanks, it's 4" right? I was thinking that cut the cat and muffler, but had some say run a 5" straight pipe from the turbo back. just wanted to know the difference of those two options.
 

·
Registered
Joined
·
3 Posts
Thanks, it's 4" right? I was thinking that cut the cat and muffler, but had some say run a 5" straight pipe from the turbo back. just wanted to know the difference of those two options.
I have a 2006 quad cab. Was my sons, now mine. He bought it with the stock exhaust still on it, then put on a 5” Diamond Eye straight pipe setup. He’s 19 and loves loud vehicles! It was loud.
When I got it, I almost immediately bought a 24” Diamond Eye muffler to quiet it down. Wasn’t enough for me, so added a 30” resonator. Ahh,... much better.

FWIW, the turbo outlet is 4”, so a 4” system is a perfect match. The 5” in my opinion is overkill and produces a ringing or bell effect that I don’t like. (Think trumpet) also, after driving a while, I had rubbing of the 5” diam. downpipe on the frame and a frame bolt, so had to ‘massage’ it with a hammer and create a couple smooth dents to clear. A 4” pipe won’t have that issue. Also, a 5” pipe has double the area (volume) as the stock 3 1/2” pipe, hence the ringing effect.
My son now has a 2014 2500/6 speed with a 4” straight pipe setup. Sounds good.👍
If you replace the exhaust, go 4”. Just my 2¢.
 

·
Registered
Joined
·
987 Posts
I have a 5" and none of the issues mentioned. May be specific to that brand. I think the 5" sounds better personally. Small amount of drone at 2000rpms on highway. Even my mother can tolerate my truck without much fuss and she hates my sports car which has longtubes and has no cats and no mufflers.

NVH is one of those things that is really hard to gauge from other people unless you know your tolerance is similar. Some people have almost no tolerance for NVH, some people have a crazy high tolerance.
 
  • Like
Reactions: RDCD

·
Registered
Joined
·
1,106 Posts
I have a 2006 quad cab. Was my sons, now mine. He bought it with the stock exhaust still on it, then put on a 5” Diamond Eye straight pipe setup. He’s 19 and loves loud vehicles! It was loud.
When I got it, I almost immediately bought a 24” Diamond Eye muffler to quiet it down. Wasn’t enough for me, so added a 30” resonator. Ahh,... much better.

FWIW, the turbo outlet is 4”, so a 4” system is a perfect match. The 5” in my opinion is overkill and produces a ringing or bell effect that I don’t like. (Think trumpet) also, after driving a while, I had rubbing of the 5” diam. downpipe on the frame and a frame bolt, so had to ‘massage’ it with a hammer and create a couple smooth dents to clear. A 4” pipe won’t have that issue. Also, a 5” pipe has double the area (volume) as the stock 3 1/2” pipe, hence the ringing effect.
My son now has a 2014 2500/6 speed with a 4” straight pipe setup. Sounds good.
If you replace the exhaust, go 4”. Just my 2¢.
The ringing effect is caused by wall thickness not diameter. Larger diameter usually produces a deeper tone.

Neither will have a difference in performance. I would expect the 4” to be a tad quieter. Less likely to drone. But I’m sure drone can be removed from both.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #8
I have a 5" and none of the issues mentioned. May be specific to that brand. I think the 5" sounds better personally. Small amount of drone at 2000rpms on highway. Even my mother can tolerate my truck without much fuss and she hates my sports car which has longtubes and has no cats and no mufflers.

NVH is one of those things that is really hard to gauge from other people unless you know your tolerance is similar. Some people have almost no tolerance for NVH, some people have a crazy high tolerance.
so what brand are you running?
 

·
Registered
Joined
·
987 Posts
  • Like
Reactions: RDCD

·
Registered
Joined
·
11 Posts
Thanks, it's 4" right? I was thinking that cut the cat and muffler, but had some say run a 5" straight pipe from the turbo back. just wanted to know the difference of those two options.
I did this on a truck I bought not long ago and ended up putting an aftermarket kit on it, it was a bit obnoxious. If you like really loud, then thats the way to go.
 

·
Registered
Joined
·
6 Posts
Great question! Bottom line is I'd go with 4." I did a lot of research on this before I bought mine. 2005, 3500 SRW, NV5600 6 spd man. I chose to go with a diamond eye 4" turbo back CAT delete through a magna flo muffler with no tip. Here's why. After reading posts on regulating EGTs I found that the difference between 4 and 5" was negligible. Most go with 5" cuz of the sound, it does sound louder. Then depending on if you go with a muffler that "may" restrict some but again its negligible if your not constantly "in it." Then the magna flo muffler I went with was one that when exhaust gases reach a certain speed or pressure it becomes just another piece of straight pipe. Hope this helps.
 

·
Registered
Joined
·
11 Posts
I put a diamondback kit on mine, its also 4in. I ordered the kit with the muffler and it was the straight through type muffler. From what I'm told, if you can't see straight through the muffler, it shouldn't be on a diesel. I would assume exhaust would flow much easier through a muffler of the type.

Not sure if you're wanting a muffler or not, however the diamondback 4in kit was a breeze to put on, and sounds good. I have an MBRP kit on my duramax and it sounds good as well, however the flange where it clamps to the turbo down-pipe rotted out on me and I ended up having to get a new one. I live in Montana and there isn't a large amount of salt here, so I'm not sure if its just perfect conditions or if MBRP uses a lesser grade of steel.
 

·
Registered
Joined
·
3 Posts
New here, I went with MBRP 5" from turbo back to muffler at rear diff. that came with kit and 4" dual exhaust coming out of muffler, sounds great, but is tight fit at firewall,
 

·
Registered
Joined
·
1,156 Posts
I have a few questions.

Did modifying your exhaust affect your MPG your EGT's and did you also modify your stock air intake.

I heard its recommended you install a EGT temp gauge and modify your air itake if you do a straight pipe conversion.
 

·
Registered
Joined
·
3 Posts
My EGTs run a little cooler and I run stock 4" air filter, but I do have a muffler now, a temp gauge is a must
 

·
Registered
Joined
·
1,156 Posts
Thanks for your info.. Replaced my stock muffler last year because it was wore out..Muffler shop installed a muffler with a little more throat and now I have a drone at low RPMs... Not a real problem as my wife hasn't complained about it while riding in the truck ...ha ha ha...
 

·
Premium Member
Joined
·
18 Posts
I’m running a 5” magnaflow setup, cat deleted. It does drone at highway speeds, but the wife hasn’t complained much being inside it. Coming from a straight piped 7.3, anything is quieter.

I wouldn’t mind a 4” instead or maybe an additional muffler/resonator. But not enough to put it on there.
 
1 - 20 of 23 Posts
Top